(1) Field of the Invention
The present invention relates to an air actuated damper that is particularly adapted for use in a furnace. In particular, the present invention relates to an air actuated damper that pivots on a cross beam mounted in the conduit. This allows the damper to swing open when air and exhaust gases are flowing out through the conduit. Likewise, when the airflow through the conduit stops, gravity causes the damper to automatically pivot on the cross beam, closing off the conduit.
(2) Prior Art
The prior art has described various types of dampers. Most of the prior art dampers have a damper blade pivotably mounted on a pivot rod or axle mounted across a flue conduit. One type of pivot rod pivots at its opposed ends which are mounted in recepticles mounted on the inside wall of the conduit. The opposed ends of the pivot rod can also extend through the conduit and have two enlarged portions at the opposed ends that retain the pivot rod across the conduit. Both of the above pivot rods have the damper blade secured to the pivot rod.
Another type of pivot rod, constructed similarly to the above described pivot rods, instead has the pivot rod secured to the conduit with the damper blade pivoting on the pivot rod. In this construction, the pivot rod is pivotably disposed through U-bolts or straps provided on the face of the damper blade. The pivot rod can also be threaded through alternating inward and outward straps forged into the damper blade. Illustrative of the latter prior art dampers is Jackson U.S. Pat. No. 4,262,608.
The problem with the prior art dampers is that they are susceptible to malfunctioning and breakdown caused by a build-up of flue particulate and ash at the point where the damper blade pivots on the pivot rod or where the pivot rod pivots on the conduit wall. Eventually, the build-up becomes so damaging that the damper blade ceases to pivot and becomes stuck in a partially opened or closed position.